Embolic Containment

ABSTRACT

Devices, systems, and methods used to seal a treatment area to prevent embolic agents from migrating are described. The concept has particular benefit in allowing liquid embolic to be used with a variety of intravascular therapeutic applications, including for occluding aneurysms and arteriovenous malformations in the neurovasculature.

RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/723,996 filed Dec. 20, 2019 entitled Embolic Containment, which is acontinuation of U.S. patent application Ser. No. 15/786,393 filed Oct.17, 2017 entitled Embolic Containment (now U.S. Pat. No. 10,555,738issued Feb. 11, 2020), which is a continuation-in-part of U.S. patentapplication Ser. No. 15/599,284 filed May 18, 2017 entitled EmbolicContainment (now U.S. Pat. No. 10,898,203 Issued Jan. 26, 2021), whichclaims benefit of and priority to U.S. Provisional Application Ser. No.62/338,387 filed May 18, 2016 entitled Embolic Shield, U.S. ProvisionalApplication Ser. No. 62/338,395 filed May 18, 2016 entitled EmbolicShield System, and U.S. Provisional Application Ser. No. 62/338,405filed May 18, 2016 entitled lntrasaccular Embolic Shield, all of whichare hereby incorporated herein by reference in their entirety.

FIELD OF THE INVENTION

The invention deals with the area of intravascular therapeutic treatmentand the use of medical devices and occlusive or embolic material totreat a vascular condition.

BACKGROUND OF THE INVENTION

Embolic agents, including embolic coils, embolic meshes, and liquidembolic among other agents are often used to occlude a target sitewithin the vasculature to treat a variety of conditions. Anon-exhaustive list of conditions includes aneurysms, atrial septaldefects, patent foramen ovale, left atrial appendage occlusion, patentductus arteriosus, fistula, arterio-venous malformations, fallopian tubeocclusion for the purposes of sterilization, spermatic vein occlusion totest infertility, and occlusion in the peripheral vasculature.

Liquid embolic is part of a newer class of compounds and are a type ofbiocompatible liquid which precipitates upon exposure to blood to hardenand occlude a treatment site. Liquid embolic, while offering someocclusive advantages, can be difficult to use since there is a high riskof the liquid embolic migrating out of the treatment site. Therefore,currently liquid embolic can only be used for a few vascular conditions.The following embodiments deal with devices, systems, and methods toseal a treatment site and prevent liquid embolic migration afterdelivery. The embodiments have particular utility in containing themigration of liquid embolic, therefore allowing liquid embolic to beused to treat a host of vascular conditions, including aneurysms andarteriovenous malformations.

SUMMARY OF THE INVENTION

The invention involves various ways of dealing with the issue of liquidembolic migration during vascular treatment, thus allowing liquidembolic to be used to treat a variety of conditions, includingconditions where liquid embolic currently cannot be used due to the riskof embolic migration.

In some embodiments, a sealing device/system which is particularlyuseful in treating sidewall aneurysms is described. The sealingdevice/system is used to seal a target treatment site, helping to keepliquid embolic within a treatment area and preventing liquid embolicfrom migrating out of the treatment area. The sealing device/system hasparticular usefulness in keeping liquid embolic within an aneurysm, suchas a sidewall aneurysm, to occlude the aneurysm.

In one embodiment, a sealing device comprises a multiple layerstructure. The multiple layers can extend through the entirety of thesealing device, or alternatively can extend through just a portion ofthe sealing device. In one embodiment, the sealing device comprises adual layer mesh—in one embodiment, the dual layer mesh includes a looserouter layer and a denser inner layer, this configuration is particularlyuseful for trapping liquid embolic in between the two layers. In anotherembodiment, the sealing device includes a multiple layer structurewherein one of the layers comprises a stent. In one embodiment, thesealing device comprises a first layer that forms the length of thedevice, and a second layer that extends through the middle of thedevice. Each mesh may have different porosity or cell size, and themeshes may expand or collapse independently of each other. In oneembodiment, the sealing device comprises an inner balloon and an outermesh layer. The various layers can be attached together or in otherembodiments can be completely independent of each other.

In one embodiment, the sealing device has a cylindrical medial sectionconfigured to face the neck of an aneurysm and tapered proximal anddistal end sections. In one embodiment, the tapered proximal and distalends have a conical shape. In one embodiment, the tapered distal end hasa rounded shape. In one embodiment, the cylindrical medial sectionincludes both an inner and outer layer where the inner layer is denserthan the outer layer, this configuration is particularly useful fortrapping liquid embolic in between the two layers. In one embodiment theinner layer is present throughout the sealing device, in anotherembodiment the inner layer is present through just the proximal andmedial sections of the device, and in another embodiment the inner layeris present through just the medial and distal sections of the device.The inner layer can be used in the distal region of the device to form acatch structure to aid in retaining embolic.

The sealing device is delivered by a pusher. In one embodiment, thepusher is a tube and includes a core wire which spans both the pusherand the sealing device. In one embodiment, the core wire can functionlike a guidewire and can be used to track a catheter and the sealingdevice. In one embodiment the core wire is completely fixed, in anotherembodiment the core wire has complete freedom of movement, in anotherembodiment the core wire has some limited freedom of movement—forexample, the core wire can move freely distally but has limited movementin a proximal direction. In some embodiments, the core wire can beconfigured so that pushing and/or pulling the core wire can affect theradial expansion/contraction of the sealing device. This property can beused to increase the radial expansion of the sealing device to aid incompletely sealing the treatment site and preventing liquid embolic fromleaking past the treatment site.

In one embodiment, a sealing system is described which has particularusefulness in sealing liquid embolic within a sidewall aneurysm. Thesystem includes an expandable structure delivered by a pusher, where thepusher includes a lumen which accommodates a core wire. The core wirespans both the pusher and the expandable structure. In some embodiments,the core wire is configured so that pushing and/or pulling the core wirecan lengthen and/or contract the expandable structure. In someembodiments, the expandable structure is a mesh device where some partsof the device have both an inner and outer mesh layer, where the innerlayer is denser than the outer layer such that the space in between thetwo layers can be used to trap embolic.

In one embodiment, a method of treating a vascular condition includesplacing a first catheter connected to a liquid embolic source within avascular condition. A sealing device or system, which comprises anexpandable structure and a pusher with a lumen therein which deliversthe expandable structure, is then placed flush with the neck or openingof the vascular condition—in one embodiment, the expandable structureincludes a cylindrical medial section and this medial section is placedflush with the neck or opening of the vascular condition. The lumenaccommodates a wire which also spans the expandable structure, where thewire can be manipulated in order to control the shape of the expandablestructure so that the expandable structure can be configured to sitflush with opening of the vascular condition. In one embodiment, theexpandable structure includes a porous outer layer and dense innerlayer. Liquid embolic is delivered through the catheter placed withinthe vascular condition, and the expandable structure prevents migrationof the liquid embolic, where the liquid embolic is trapped between theinner and outer layers of the expandable structure. In one embodiment,the vascular condition treated in an aneurysm. In one embodiment, thevascular condition treated is a sidewall aneurysm.

In some embodiments, a sealing device/system, which is particularlyuseful in treating bifurcation aneurysms, is described. The sealingdevice/system has particular usefulness in keeping liquid embolic withinan aneurysm, such as a bifurcation aneurysm, to occlude the aneurysm.

In one embodiment, a sealing device includes an occluder where theoccluder is an intrasaccular agent which sits completely within thetreatment site. In another embodiment, the occluder is a neck seal whichsits at the neck of the treatment site—where either a portion of theoccluder can sit within the treatment site, or all of the occluder cansit outside of the treatment site. In one embodiment, the occluderincludes a first region and a second region where the regions areseparated by a narrowed section. In one embodiment, the occluderincludes foldable layers. In one embodiment, the occluder is comprisedof a mesh of wires. In one embodiment, the occluder includes a polymericcoating.

A tension wire is pushed and pulled to lengthen and compress the shapeof the occluder. In one embodiment, the tension wire is selectivelyremovable from the occluder. In one embodiment, the tension wire isselectively removable from the occluder via a threaded mechanicalconnection. The occluder is delivered by a pusher. In one embodiment,the occluder is connected to the distal part a pusher and is detachablefrom the pusher so that after detachment, the pusher lumen cansubsequently be used to deliver additional embolic agents, includingliquid embolic.

In one embodiment, a sealing device includes an occluder with a coiledelement connected to a distal portion of the occluder. The tension wireconnects to the coiled element. In one embodiment, the tension wire isselectively removable from the coiled element. In one embodiment, thetension wire is selectively removable from the coiled element via athreaded mechanical connection.

In one embodiment, a sealing system which has particular usefulness insealing liquid embolic within a bifurcation aneurysm includes anoccluder, a pusher used to push the occluder, and a tension wirespanning both pusher and the occluder. The tension wire can bemanipulated in order to compress and lengthen the occluder. The tensionwire is removable from the occluder and pusher. Once the tension wire isremoved, the pusher can be used to deliver additional embolic agents,including liquid embolic, through the occluder. In one embodiment, theoccluder is detachable from the pusher.

In one embodiment, a method of treating a vascular condition includesdelivering a sealing device or system—which comprises an occluder,tension wire, and pusher tube—where a portion, or all of the occludersits outside the vascular condition. A tension wire spans the pusher andoccluder and is used to control the shape of the occluder. The tensionwire is optionally removed from the occluder and withdrawn through thepusher. The pusher is subsequently used to deliver a liquid embolic. Inone embodiment, the vascular condition treated is a bifurcationaneurysm.

In some embodiments, a sealing device/system which is particularlyuseful in treating arteriovenous malformations (AVM's) is described. Thesealing device has particular usefulness in keeping liquid embolicwithin an AVM, to occlude the AVM.

In one embodiment, a sealing device comprising a catheter and a catch orshield structure placed on a distal region of a catheter is described.In one embodiment, the catch comprises a mesh or braid comprised ofwires. In one embodiment, the catch is detachable. In one embodiment, adetachment system for detaching a catch is described.

A method of embolic delivery is described in some embodiments. Acatheter connected to a liquid embolic source is navigated through thevenous side of the vasculature, to the location of an AVM. The proximalsection of the catheter includes a port for liquid embolic injection.The distal region of the catheter includes a catch and a lumen forliquid embolic delivery. Liquid embolic is delivered through thecatheter into the AVM, and the catch ensures any liquid embolic backflowis caught so that liquid embolic does not collect in the venous side ofthe vasculature. In one embodiment, the catch is optionally detachablefrom the catheter, where a detachment sequence may be initiated todetach the catch.

A method of embolic delivery utilizing two catheters is described insome embodiments. A first catheter is connected to a liquid embolicsource and is navigated through the arterial side of the vasculature tothe location of an AVM. A second catheter includes a distal catch and isnavigated through the venous side of the vasculature near the locationof an AVM. The first catheter delivers liquid embolic from the arterialside of the AVM, and the second catheter's catch structure is used tocatch any liquid embolic that flows through the AVM to the venoussystem. The second catheter therefore operates as a catch, ensuringliquid embolic delivered from the arterial side of the AVM does not endup in the venous system. In one embodiment, both catheters are used todeliver liquid embolic so that the AVM is occluded from both thearterial side and the venous side, and the second catheter's catch onthe venous side of the AVM ensures no liquid embolic migrates in thevenous system of the vasculature.

An AVM treatment procedure is described in some embodiments. In oneembodiment, a catheter is tracked through the venous system of thevasculature, to a point near an AVM. The catheter includes a catch onthe distal region of the catheter. Liquid embolic is delivered throughthe catheter into the AVM to occlude the AVM. Any embolic backflow iscaught by the catch. In one embodiment, the catch is optionallydetachable from the catheter. Once the AVM is occluded, normal bloodflow through the artery, capillaries, and veins is preserved.

In another embodiment, an AVM treatment procedure utilizes twocatheters—a first catheter is connected to a liquid embolic source and asecond catheter contains a distal catch. The first catheter is trackedthrough the arterial system to the location of an AVM. The secondcatheter is tracked through the venous system and is tracked to thelocation of an AVM, such that the first and second catheters are onopposite sides of the AVM. Liquid embolic is delivered through the firstcatheter such that the AVM is occluded with liquid embolic from thearterial side of the AVM. The catch on the second catheter, which sitson the venous side of the AVM, catches any embolic which migrates fromthe AVM ensuring that liquid embolic does not end up in the venoussystem. In one embodiment, both catheters are connected to liquidembolic sources and are used to deliver liquid embolic so that the AVMis occluded from both the arterial side and the venous side, and thesecond catheter's catch on the venous side of the AVM ensures no liquidembolic migrates in the venous system of the vasculature.

A catheter is described in some embodiments. In one embodiment, thecatheter comprises a catch located at the distal portion of thecatheter. In one embodiment, the catch is detachable from the catheterand the catheter includes a detachment system which is optionally usedto detach the catch. In one embodiment, the catheter is used for liquidembolic injection to treat AVM's.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other aspects, features and advantages of which embodiments ofthe invention are capable of will be apparent and elucidated from thefollowing description of embodiments of the present invention, referencebeing made to the accompanying drawings, in which:

FIG. 1 illustrates a sealing device used to treat an aneurysm, accordingto one embodiment.

FIG. 2 illustrates an inner and an outer mesh of a sealing device,according to one embodiment.

FIG. 3 illustrates a pusher delivery system used with a sealing devicewhere the sealing device is in an expanded configuration, according toone embodiment.

FIG. 4 illustrates a pusher delivery system used with a sealing devicewhere the sealing device is in a collapsed configuration, according toone embodiment.

FIG. 5 illustrates a core wire with a coiled distal tip used with asealing device, according to one embodiment.

FIG. 6 illustrates a core wire with a bent distal tip used with asealing device, according to one embodiment.

FIG. 7 illustrates a cross-section of a guide or access catheter used todeliver a sealing device and embolic agent, according to one embodiment.

FIG. 8 illustrates a sealing device having a rounded distal section,according to one embodiment.

FIG. 9 illustrates a cross-section of a dual-layer sealing device,according to one embodiment, and how liquid embolic would be trappedbetween the two layers.

FIG. 10 illustrates a bifurcation aneurysm.

FIG. 11 illustrates an occluder used in a sealing device, according toone embodiment.

FIG. 12 illustrates the occluder from FIG. 11 in an expandedconfiguration, according to one embodiment.

FIG. 13 illustrates a sealing system in a collapsed state duringdelivery, according to one embodiment.

FIG. 14 illustrates a sealing system in a delivered state where anoccluder used in the system adopts a stretched configuration, accordingto one embodiment.

FIG. 15 illustrates a sealing system in a delivered state where anoccluder used in the system adopts a radially expanded configuration,according to one embodiment.

FIG. 16 illustrates the sealing system of FIG. 15 where the tension wireis withdrawn, according to one embodiment.

FIG. 17 illustrates a sealing system after delivery to a target site,according to one embodiment, where a pusher tube is used to deliverembolic.

FIG. 18 illustrates a sealing system used in a bifurcation aneurysm,according to one embodiment, where liquid embolic is delivered into thebifurcation aneurysm.

FIG. 19 illustrates a sealing system used in an aneurysm, according toone embodiment, where delivered liquid embolic has solidified to createan occlusive mass along with an occluder.

FIG. 20 a illustrates a normal arterial-capillary-venous intersection.

FIG. 20 b illustrates an arteriovenous malformation (AVM), including thenidus, feeder vessels, and draining vein.

FIG. 21 illustrates an arteriovenous malformation (AVM), along anarterial-venous intersection.

FIG. 22 illustrates a typical delivery procedure to occlude an AVM withliquid embolic.

FIG. 23 illustrates a liquid embolic delivery procedure to occlude anAVM, according to one embodiment, utilizing a microcatheter with acatch/shield which is used to deliver liquid embolic from the venousside of an AVM.

FIG. 24 illustrates a liquid embolic delivery procedure used to occludean AVM, according to one embodiment, utilizing a first microcatheter todeliver liquid embolic from the arterial side of an AVM and a secondmicrocatheter with a catch/shield used to catch embolic on a venous sideof an AVM.

FIG. 25 illustrates a catheter with a conically-shaped catch, accordingto one embodiment.

FIG. 26 illustrates a catheter with an elongated-shaped catch, accordingto one embodiment.

FIG. 27 illustrates a catheter with a trumpeted-shaped catch, accordingto one embodiment.

FIG. 28 illustrates a microcatheter with a catch structure beingdelivered through a larger guide or access catheter, according to oneembodiment.

FIG. 29 illustrates a microcatheter with a catch in a partiallydelivered state through a larger guide or access catheter, according toone embodiment.

FIG. 30 illustrates a microcatheter with a catch in a delivered statewhere the embolic shield is free of the larger guide or access catheter,according to one embodiment.

FIG. 31 illustrates a detachment system used to detach a catch from acatheter, according to one embodiment.

FIG. 32 illustrates a microcatheter with an attached collapsed catch,according to one embodiment.

FIG. 33 illustrates the microcatheter and catch in FIG. 32 where part ofthe catch is no longer attached to the microcatheter, according to oneembodiment.

FIG. 34 illustrates the microcatheter and catch from FIG. 32 wherein thecatch adopts an inverted configuration, according to one embodiment.

DESCRIPTION OF EMBODIMENTS

Specific embodiments of the invention will now be described withreference to the accompanying drawings. This invention may, however, beembodied in many different forms and should not be construed as limitedto the embodiments set forth herein; rather, these embodiments areprovided so that this disclosure will be thorough and complete, and willfully convey the scope of the invention to those skilled in the art. Theterminology used in the detailed description of the embodimentsillustrated in the accompanying drawings is not intended to be limitingof the invention. In the drawings, like numbers refer to like elements.

Occlusion or embolization is a technique used to treat a variety ofintravascular conditions, such as aneurysms, atrial septal defects,patent foramen ovale, left atrial appendage occlusion, patent ductusarteriosus, fistula, arterio-venous malformations (AVM), fallopian tubeocclusion for the purposes of sterilization, spermatic vein occlusion totest infertility, and occlusion in the peripheral vasculature. Topromote occlusion, embolic material such as embolic coils or embolicmeshes are used to fill the treatment site (e.g. aneurysm), which overtime cuts off blood flow to the site, promotes clotting, and—in the caseof aneurysms—helps prevent vessel rupture which could otherwise lead tostroke.

Liquid embolic is part of a newer class of embolic agents. Some liquidembolic embodiments are described in U.S. Pat. No. 9,078,950, which ishereby incorporated by reference in its entirety. Liquid embolic is aviscous biocompatible liquid. The liquid embolic precipitates afterexposure to blood or aqueous solutions. Many varieties of liquid embolicare mixed with dimethyl sulfoxide (DMSO) solvent to prevent earlysolidification. Upon delivery through the delivery catheter and into thetreatment site, the DMSO will rapidly diffuse away causing the embolicmaterial to precipitate due to exposure to blood. The precipitatedembolic will occlude the treatment site, preventing blood flow into thetarget area. Liquid embolic is currently used to treat AVM's, however,using liquid embolic to treat other vascular conditions such asaneurysms is difficult since the embolic can migrate to other areas ofthe vasculature prior to solidifying, or can solidify and still migrateto other areas of the vasculature. Stents cannot be used to seal theaneurysm treatment area since stent pore sizes are too large to preventoutflow of liquid embolic and the open ends of the stent provide an easyescape path for embolic. Additionally, even when liquid embolic is usedto treat AVM's there is still a risk of embolic migration.

The present invention addresses the issues associated with liquidembolic migration by providing a sealing device/system that sufficientlyseals a target treatment site to prevent migration of embolicmaterial—thereby allowing liquid embolic to be used in a variety oftherapeutic procedures, such as treating aneurysms, where it currentlycannot be used due to the risk of embolic migration.

For the purposes of illustrative ease, the sealing device, systems, andmethods going forward will be described primarily in the treatment ofaneurysms and AVM's. Though the following embodiments have particularutility when used with aneurysms and/or AVM's they are not limited tothis application and can be used to treat a variety ofconditions/vascular malformations including aneurysms, atrial septaldefects, patent foramen ovale, left atrial appendage occlusion, patentductus arteriosus, fistula, arterio-venous malformations, fallopian tubeocclusion or spermatic vein occlusion for the purposes of sterilization,and occlusion in the peripheral vasculature.

The following embodiments shown in FIGS. 1-9 and described below haveparticular usefulness in treating aneurysms, including sidewallaneurysms. Aneurysms occur when there is a weakened region along thewall of a blood vessel; this weakened region develops into a protrudingbulge which can eventually rupture leading to complications such asstroke when these aneurysms occur in the neurovasculature. Sidewallaneurysms occur along the sidewall of a blood vessel. Liquid embolicgenerally cannot be used to treat sidewall aneurysms due to the highrisk of liquid embolic migration prior to solidification or even aftersolidification, where the liquid embolic can migrate elsewhere leadingto major complications. The following embodiments are geared towards asealing device that is placed against the opening of the aneurysm tocontain liquid embolic within the aneurysm.

Stents are sometimes used to treat aneurysms, where the stent is an openended tubular structure placed across the neck of the aneurysm. Flowdiversion stents are stents with relatively small pore sizes, where thesmaller pore sizes limit blood flow to the aneurysm closing off accessto the aneurysm over time. Assist stents are also used, and these assiststents include pores and a microcatheter is placed within the stentpores to deliver embolic coils into the aneurysm to occlude the aneurysmin a procedure known as stent assisted coil embolization. Neither typeof stent can be used with liquid embolic delivery for a variety ofreasons. First, the proximal and distal open ends of a stent provide aneasy escape path for liquid embolic which might seep through the stent,heightening the risk of occlusion and stroke elsewhere in thevasculature based on migration of the embolic formation. Second,assist-stents include large pores in order to accommodate amicrocatheter which is delivered through the pores—these pores are toolarge to prevent the passage of liquid embolic material.

FIG. 1 shows a sealing device 100 according to one embodiment, and inparticular illustrates how the sealing device 100 would be positionedrelative to an aneurysm 134, in this case a sidewall aneurysm.Microcatheter 130 is positioned within the aneurysm to deliver liquidembolic and sealing device 100 is placed to block the neck of theaneurysm. Sealing device 100 prevents the delivered embolic materialfrom migrating from aneurysm 134. In one embodiment, sealing device 100generally has a cylindrical center section 132 c and tapered endsections 132 a and 132 b. The tapered end sections provide a generallyclosed proximal and distal end section, which helps to prevent thepassage of liquid embolic where liquid embolic migrates through thesealing device. Please note, the term taper refers to involving adiameter reduction in a particular direction. For the purposes of FIGS.1 , the particular shape shown is conical type of taper, though othertapered shapes are also possible. Cylindrical center section 132 c canbe thought of as representing the working length of the device since, asshown in FIG. 1 , this section will sit in the blood vessel over theneck of the aneurysm to help seal the neck of the aneurysm and preventembolic discharge from the aneurysm.

Sealing device 100 is expandable, adopting a collapsed shape duringdelivery through a catheter and an expanded shape once delivered fromthe catheter. In this way, sealing device 100 can be thought of as anexpandable structure. Sealing device 100 includes a core wire 118spanning the sealing device, as will be explained in more detail later.Core wire 118 is used to manipulate the shape of the sealing device 100such that retracting the core wire causes the sealing device 100 toradially expand and therefore help seal a treatment area. In thismanner, core wire 118 can be thought of as a controller, morespecifically an expandable structure controller, where the core wire canbe used to control the shape of the expandable structure sealing devicein order to allow the sealing device to adopt an optimal shape to seal atreatment area and prevent liquid embolic discharge out of the vasculartreatment site.

As mentioned earlier, several types of liquid embolic are deliveredalong with DMSO to keep the liquid embolic from prematurelyprecipitating and solidifying. The liquid embolic solidifies onceexposed to blood, and the DMSO which is delivered along with the liquidembolic dissipates through the bloodstream. Sealing device 100 acts as arestraining agent to help keep the liquid embolic in aneurysm 134 andkeep liquid embolic from migrating elsewhere in the vasculature—forexample, in scenarios where the liquid embolic does not immediatelyprecipitate and a portion of it may migrate out of the aneurysm beforesolidification, or in scenarios where a portion of the precipitatedliquid embolic may migrate out of the aneurysm.

In one embodiment, the sealing device 110 comprises two layers—an innerlayer 112 a and outer layer 114 a as shown in FIG. 2 . In oneembodiment, the inner and outer layer are both meshes comprised ofmetallic wires. The metallic wire mesh can include some nitinol and someradiopaque (e.g. tantalum, platinum, gold) wires, the inclusion ofradiopaque wires will aid in visualization. Alternatively, the wires cancomprise a nitinol core with a radiopaque exterior, or a radiopaque corewith a nitinol exterior. Alternatively, one of the mesh layers caninclude solely nitinol wires while the other mesh layer includes bothnitinol and radiopaque wires. In one embodiment, the inner layer 112 amesh and/or outer layer 114 a mesh could be comprised of drawn-filledtubing (DFT). DFT utilizes an inner core material surrounded by an outerjacket and is described in U.S. Pat. No. 7,420,124 which is herebyincorporated by reference in its entirety. The inner core can compriseone or more wire elements. By using different materials for the innerlayer and outer jacket, it is possible to create a mesh utilizingdifferent material properties. In one embodiment, DFT utilizing aplatinum inner core and a nitinol outer jacket is used. The platinuminner core would augment radiopacity and aid in visualizing the devicewhile the nitinol outer jacket would provide good shape memoryretention. The sealing device should have a good amount of shape memory,which a nitinol wire-based device should have due to the strongshape-memory properties of nitinol. Known heat treatments to impartshape memory, such as heat treatment over a mandrel shaped to the shapeof the sealing device, can be used to impart this shape memory. Theshape memory would mean the sealing device 110 could adopt a collapsedshape when housed within a microcatheter, and then an expanded shapeupon release from the microcatheter due to the imparted shape memory.The sealing device can therefore be thought of as an expandablestructure which adopts a collapsed configuration when housed in amicrocatheter, and an expanded configuration when freed from saidmicrocatheter.

In one embodiment, inner layer 112 a and outer layer 114 a are attachedtogether. Mechanical ties can be selectively placed throughout thelength of both layers to attach the layers to each other. Alternatively,a wire can be woven with the two layers in an alternating pattern (e.g.below the bottom layer, above the top layer, below the bottom layer,above the top layer, etc.) in order to bind the layers together. Inanother embodiment, no attachment means are used between thelayers—instead, each layer is formed of shape memory material and thebuilt-in shape memory of the layers will allow each layer to expand oncethe sealing device is pushed out from the delivery catheter. The amountof built-in shape memory and size of the blood vessel, would inherentlycontrol the expansion of both layers. Known heat treatments to impartshape memory, such as heat treatment over a mandrel shaped to the shapeof the sealing device, can be used to impart this shape memory. Nitinolhas a particularly good shape memory quality, so the layers couldinclude at least some nitinol wires in the mesh to impart strong shapememory within the layers of the sealing device.

In one preferred embodiment, the inner layer 112 a is comprised of adenser mesh than the outer layer 114 a. Where the sealing device is usedto retain liquid embolic material delivered through a microcatheter 130(as shown in FIG. 1 ), the looser outer layer might allow some liquidembolic through, but the denser inner mesh would catch the liquidembolic and prevent it from permeating through the inner mesh. Thisembodiment would be made by using a mandrel to braid a dense mesh, andusing a mandrel to braid a looser outer mesh. The looser outer meshwould be placed over the denser, inner mesh. Optional attachments, asdiscussed above, could be subsequently used to bind the layers. Sincethe sealing device does not need to accommodate a microcatheter, innerlayer 112 a can be particularly dense to help prevent the passage ofliquid embolic through the inner layer and through the sealing device.As a failsafe, the tapered proximal and distal ends 132 a, 132 b of thesealing device provide a catch structure to catch any displaced liquidembolic.

In one embodiment, the looser outer layer comprises the length of thedevice, and the denser inner layer sits within solely the middle sectionof the device. The middle section 132 b sits against the entrance to theaneurysm as shown in FIG. 1 , the denser inner braid of the device willtherefore be aligned with the neck of the aneurysm and catch any looseor migrating embolic from the aneurysm. Meanwhile, the proximal anddistal ends 132 a, 132 b of the device comprise solely the looser outermesh—and not the denser inner mesh—to enable blood and DMSO to flowunperturbed through these regions of the sealing device.

In another embodiment, the looser outer layer is used along the completelength of the device and the middle 132 c and distal 132 b sections ofthe device utilize a dense inner layer. This may be preferable to helpensure liquid embolic cannot migrate distally—as the dense distal end ofthe device would act like a catch if embolic happened to seep throughthe inner layer. Since these devices are typically placed in thedirection of blood flow, one can imagine blood flowing left to right andthe device being placed so that the proximal end 132 a is to the leftand the distal end 132 b is to the right. Since blood flows toward the‘right’ or distal side, having the catch on the distal or ‘right’ sideis preferable since the embolic could migrate downstream. In thisembodiment, any liquid embolic making it past the dense inner layer 112a of the middle section 132 c of the device would encounter anotherdense inner layer 112 a and a looser outer layer at distal taperedregion 132 b. Even in situations where the inner layer is not used onthe distal tapered section 132 b of the device, the device can easily beconfigured so that the distal tapered section 132 b is denser than othersections of the device—in other words, the outer layer 114 a can bedesigned so that the outer layer at the distal tapered section 132 b isless porous than the outer layer in the medial section 132 c of thedevice.

In one embodiment, the denser inner mesh will prevent the liquid embolicagent from entering, trapping the liquid embolic between the inner andouter layer and forming a thin film between the two layers, which willallow the inner layer to collapse to aid in retrieval. Since DMSO isless viscous than pre-precipitated liquid embolic (and certainly lessviscous than solidified or precipitated liquid embolic), a denser distaltapered end 132 b should not impact the ability of DMSO and blood toflow through this region since DMSO and blood are substantially lessviscous than liquid embolic.

Other embodiments could utilize additional layers, for instance three ormore layers where the mesh density profile of each layer could vary fromthe other layers. Other embodiments could utilize a sealing devicecomprising polymers instead of a metallic mesh structure. Otherembodiments could utilize a combination of polymers and metallic meshesuse to create the sealing device. Other embodiments could utilize asolid multi-layer tubular structure which is laser-cut to create poreson each layer. Other embodiments could utilize a stent as the innerlayer, where a mesh with tapered proximal and distal sections is placedover the stent to create a multi-layer structure.

In one embodiment, the cylindrical medial section/working length portionof the device 132 c can utilize radiopaque components to aid invisualization so the user can tell where the working length of thedevice is placed relative to the aneurysm. In one example, radiopaquemarker coils or marker bands made of platinum, tantalum, or gold can beselectively placed throughout section 132 c of the device so thissection of the device is particularly visible.

The sealing device includes a distal marker 116 shown in FIGS. 1 and 3-4, which is a radiopaque marker band comprising a radiopaque substancesuch as gold, tantalum, platinum, or palladium that can be used to crimpthe distal end of the outer layer mesh. A marker band (not shown) couldalso be used at the proximal end of the device to crimp the proximal endof the outer layer mesh. The marker band would include a lumen; themarker band could therefore be thought of as a hollow cylinder or tube.The radiopaque marker would be useful for imaging purposes to visualizethe ends of the device to aid in placement of the sealing devicerelative to the vascular condition. A core wire 118 spans the length ofthe device and also spans a hypotube delivery pusher 122 proximallyconnected to the sealing device 110 which is used to deliver (push/pull)the sealing device 110 through a catheter—as shown in FIGS. 3-4 . Corewire 118 sits through the marker band lumen. Core wire 118 can be madeof a variety of materials, such as a metallic (e.g. nitinol or stainlesssteel) wire or hypotube; alternatively a radiopaque substance such atantalum, platinum, gold, or tungsten can be used. In one embodiment,core wire 118 is made of a nitinol wire which is wrapped with aradiopaque coiled wire to aid in visualizing the core wire. The deliverysystem and method of delivery utilizing core wire 118 will be discussedin more detail later.

FIGS. 3-4 show the delivery system for the sealing device, according toone embodiment. Sealing device 110 is connected to the distal end of ahypotube pusher 122. The pusher is controlled from the proximal end ofthe system by the user to push and pull both the hypotube 122 and theattached sealing device 110 through a microcatheter 128 and through thevasculature. The hypotube pusher is a tube and includes an interiorchannel or lumen. Core wire 118 sits within this channel and runs fromthe proximal end to the system—where it is manipulated by the usersimilar to a guidewire to track the guidewire and catheter through thevasculature—to the distal end of the system where it sits distal of thesealing device. The proximal portion of the sealing device 110 isaffixed to the distal end of hypotube 122. In one example, the proximalportion of the sealing device 110 is affixed via welding, adhesive, orsimilar means to the interior of the hypotube at location 124—though theproximal end of sealing device 110 could also be affixed to the outsideof the hypotube at location 124. In one embodiment, there are nodetachment means to detach the sealing device from the hypotube. Sincethe sealing device is meant to be used just to prevent embolic migrationfrom the aneurysm, once the liquid embolic is injected within theaneurysm and the embolic precipitates to occlude the aneurysm, thesealing device is removed from the vasculature. This can be accomplishedby retracting the hypotube pusher proximally through microcatheter 128,which is also used to deliver the sealing device. However, inalternative embodiments, it would be easy to introduce a detachmentsystem at the distal part of the hypotube pusher to detach the sealingdevice—electrolytic, mechanical, or thermal means could be used. In oneexample there is a sacrificial element between the sealing device andhypotube (e.g. at location 124 of FIGS. 3-4 ) that is thermally,electrolytically, or mechanically degraded in order to detach thesealing device. US20100269204, US20110301686, US20150289879 all describethermal detachment systems and are hereby incorporated by reference intheir entirety.

FIGS. 5-6 show two embodiments of the core wire 118 which spans thelength of the sealing device. FIG. 5 shows the core wire 118 culminatingin a distal coiled tip 120 which passes through the lumen of distalmarker 116 and sits distal of marker 116. The coiled tip is comprised ofa coil; a coil shape is useful since if the distal tip hits a vessel,the coiled tip allows for some flexibility which reduces the likelihoodthat the tip will get stuck or stab into the vessel wall. FIG. 6 showsthe core wire 118 culminating in a bent tip 120. Bent tip 120 is moremalleable than the rest of the core wire and is meant to be bent in anydirection. The user would pre-shape the distal tip by bending itphysically, or using a mandrel or tool to bend the distal tip in aparticular direction. This bent shape is desirable so that if the wireis being navigated through the vasculature and there is a bifurcation,the user can rotate the wire so that the bent tip aligns with thecorrect vessel, and the wire can then be pushed through the appropriatevessel. This bent shape configuration, known as a J-shape in the art, ifoften used on guidewires to aid in tracking a guidewire through tortuousanatomy, particularly at bifurcations where a user must be able toselect a particular vessel—the user will rotate or manipulate theguidewire into the desired vessel at a bifurcation point and thencontinue to track the guidewire.

Generally in order to access a vascular treatment site, a guidewire isfirst introduced into the vasculature and large-lumen guide or accesscatheter is tracked over the guidewire to access the treatment site. Theguide or access catheter provides an access path for a smallermicrocatheter which is used to deliver a medical device or therapeuticmaterial to the target region. The guidewire is a thin, navigable wireused solely to access a target region, and the guidewire is withdrawnonce the target region is accessed. The inclusion of core wire 118 whichspans the sealing device would allow the core wire, in essence, tofunction like a guidewire and be used to track the catheter to thetreatment site—in a manner that will now be described.

In one embodiment, the core wire 118 and core wire distal tip 120 (seeFIGS. 3-6 ) is freely moveable, such that the core wire 118 is notaffixed to anything and is freely moveable through sealing device 110and can even be completely removed by pulling the core wire 118 toretract it through the sealing device 110 and completely out of thevasculature if so desired by retracting the core wire completely. Inpractical terms, this means the lumen within marker band 116 would belarger than the core wire 118 diameter and core wire distal tip 120diameter. Core wire 118 could function as a guidewire since the corewire 118 could be pushed far distally of the sealing device 110 and thenused to track the sealing device and catheter 128.

In another embodiment, the core wire 118 could be freely movabledistally but distal tip 120 is larger than the marker band 116 lumen sothat the distal tip 120 is not retractable through the sealing device110. In practical terms, this means the core wire distal section 120 isthicker than the rest of core wire 118 and is also thicker than thedistal marker 116 lumen and would therefore contact the distal marker116 upon retraction, limiting the amount of proximal movement of thecore wire. Allowing some free distal mobility of the core wire distalsection 120 would allow for configurations like the one described above,where the core wire 118 could function like a guidewire and where thecore wire 118 could be used to track the sealing device 110 andmicrocatheter 128. Since the core wire 118 is distally pushable, theuser could simply push the core wire 118 so that the distal tip 120 ofthe core wire sits far beyond the distal end of the sealing device 110and far beyond the distal end of the catheter 124 that the sealingdevice 110 is delivered through. The sealing device 110 and catheter 124could then be tracked over the core wire 118. Retracting core wire 118would cause core wire distal tip 120 to contact marker band 116,applying a sufficient retraction force on core wire 118 would causesealing device 110 to radially expand and longitudinally contract due tothe force exerted by distal tip 120 on marker band 116 and sealingdevice 110. The ability to control the radial shape of the sealingdevice in this manner will be appreciated later.

In another embodiment, the core wire distal tip 120 is not freelymovable and adopts a fixed position. In one embodiment, the core wiredistal tip 120 is in a fixed position far distal of the sealing deviceand the sealing device, as it contracts and expands (e.g., duringdelivery), can float over the fixed core wire—so that the sealing devicecan be pushed over the fixed core wire via the pusher 122. In oneembodiment, a tightening mechanism such as a collet can be used toselectively lock core wire 118 in a fixed position—this collet would sitat a proximal location, such that a user could tighten the collet tolock the core wire 118 or loosen the collet to move the core wire 118.In one embodiment, this fixed position is achieved by affixing core wire118 or the core wire distal tip 120 directly to distal marker 116 sothat core wire 118 is fixed and not freely movable; this can be done viawelding or adhesives. In one example, core wire 118 is welded oradhesively affixed to the interior or exterior of the marker band 116.In another example, core wire distal tip 120 is thicker than the rest ofcore wire 118 and the distal tip 120 is mechanically affixed (viaadhesive or welding) to distal marker band 116. One advantage of thesystem where the core wire is affixed to distal marker 116 is thatpulling on core wire 118 will pull the distal marker 116 proximallysince the core wire and marker are connected, thereby radially expandingthe shape of the sealing device—this happens since the sealing device islinked to the hypotube at one end and to the distal marker and the corewire at the other end. Similarly, pushing on the core wire will elongatethe sealing device and cause it to adopt a more elongate, less radiallyfull profile. The ability to control the radial shape of the sealingdevice in this manner will be appreciated later. Where a fixed core wire118 configuration is used, the portion of core wire 118 sitting withincylindrical medial section 132 c of the device can utilize a radiopaquecomponent (e.g. the radiopaque coiled wire surrounding a nitinol wirediscussed earlier) to aid in visualizing cylindrical section 132 c ofthe device.

Referencing FIG. 1 , a microcatheter 130 used to deliver liquid embolicis placed within the aneurysm 134 and a sealing device 100 issubsequently placed to seal the aneurysm. The sealing device isdelivered through a separate microcatheter 128, as shown in FIGS. 3-4 .Because multiple microcatheters are needed (one microcatheter to deliverthe sealing device, and another to deliver the liquid embolic), deliveryof two separate microcatheters can be an issue given the time needed totrack two separate microcatheters through the vasculature. In oneembodiment, both microcatheters 128 and 130 are placed through a largerlumen guide or access catheter 126—as shown in FIG. 7 . Thisconfiguration can be achieved in a number of different ways. Forexample, the larger delivery catheter 126 can include two lumens, andthese individual lumens provide access for microcatheters 128, 130.Alternatively, the larger delivery catheter has a single lumen andmicrocatheters 128, 130 are both placed within this lumen. Alternativelystill, the larger delivery catheter 126 contains two lumens and one ofthese lumens is used to deliver embolic and the other lumen is used todeliver the sealing device (in essence, the open lumens themselves wouldact like microcatheters). For illustration, the guide or access catheter126 can be 6 or 7 French size (about 2-2⅓ mm outer diameter), whilemicrocatheters 128, 130 are 2 or 3 French size (about ⅔-1 mm outerdiameter). For inner diameter illustration, microcatheters 128 and 130can have an inner diameter of 0.017, 0.021, or 0.027 inches. These sizesare purely for illustration and the sizes of the microcatheters anddelivery catheter can be sized up or sized down as needed.

A separate guidewire can be used to navigate the guide/access catheter126 near the target treatment site (for example, the guidewire can beplaced within one lumen, and then retracted once the treatment site isaccessed). Alternatively, core wire 118 which is used with sealingdevice 110 can function as the guidewire as discussed in previousembodiments where core wire 118 has some degree of freedom of distalmovement such that the core wire distal tip 120 can be advanced and thesealing device/system can be advanced over the core wire.

Sealing device 110 is delivered through microcatheter 128, and thesealing device is placed at the distal end of a hypotube pusher as shownin FIGS. 3-4 . When guide or access catheter 126 is tracked near thetarget treatment site (e.g. near the vicinity of the aneurysm),microcatheter 130—which is used to deliver the embolic to the aneurysm,is first pushed out so that it sits within aneurysm 134 (or,alternatively, guide/access catheter 126 is retracted to exposemicrocatheter 130)—as shown in FIG. 1 . Microcatheter 128 is then alsopushed out from the delivery catheter (or, alternatively, guide/accesscatheter 126 is retracted to expose microcatheter 128). Hypotube pusher122 is then pushed (or microcatheter 128 is retracted) so that sealingdevice 110 is released from microcatheter 128. The sealing device 110 isplaced appropriately under the neck of the aneurysm in order to seal theaneurysm. Sealing device 110 should be placed similar to theconfiguration shown in FIG. 1 , where the cylindrically-shaped medialportion 132 c of sealing device 100 seals the neck of aneurysm 134 andwhere microcatheter 130 is pinned against the sealing device 100. Onepotential complication of microcatheter 130 being pinned against sealingdevice 100 is that there may still be a small gap in between themicrocatheter 130 and sealing device 100 which results in sealing device100 not completely sealing the area under the neck of aneurysm 134. Thissmall gap would mainly present toward the proximal portion of thesealing device, since the microcatheter would mainly contact the sealingdevice on the proximal part of the sealing device (as shown in FIG. 1 )and the self-expanding nature of the sealing device would tend to coversome of the open area distal of the interface between microcatheter 130and sealing device. This small gap could possibly provide an escape pathfor embolic which could migrate out of the aneurysm and not get caughtby sealing device 100. Earlier embodiments discussed one concept wherecore wire 118 is fixed to distal marker 116 and another concept wherecore wire distal tip 120 is thicker than marker band 116 and cannot beretracted past marker band 116, and how the core wire can be pulled toradially expand the sealing device. This system can be used to radiallyexpand the sealing device so that no gap is present between the aneurysmand sealing device, which could otherwise allow embolic to seep out ofthe aneurysm and not get caught by the sealing device. Thus, the usercould simply retract wire 118 (see FIG. 1 ) to expand the sealing deviceand seal any gap between microcatheter 130 and the area underneath theaneurysm. Since wire 118 can be used to manipulate and control the shapeof the expandable sealing device, wire 118 can be thought of as anexpandable structure controller/control mechanism. However, note thateven if a small gap is present, the blood flow proceeds in a downstreamdirection (i.e. left-to-right in FIG. 1 ), so the inclusion of a tightdistal mesh/catch structure along distal section 132 b, would also helpcatch the embolic if it leaks. Additionally, microcatheter 130 would,itself, fill much of the proximal gap space.

Once the liquid embolic starts filling the aneurysm, it may migrate pastthe neck of the aneurysm prior to solidifying—or portions of the liquidembolic may solidify but still break away from the larger embolic mass.Some embolic may get past the more permeable outer layer (114 a, seeFIG. 2 ) of sealing device 110, however the embolic will get caught bythe less permeable inner layer of the sealing device. Ideally, there isa small gap in between the inner and outer layers of the sealingdevice—this small gap provides a catch area for the liquid embolic suchthat the embolic is caught between the gap defined by the outer 114 aand inner 112 a layers of sealing device 110. Where attachment means areused between the two layers, as discussed earlier, the number ofattachment points or the tightness of the wire wound through the layerwill affect the gap size in between the two layers. More attachmentpoints, or a tighter wire winding through the layers would result in asmaller gap; while fewer attachment points or a looser wire windingthrough the layers would result in a larger gap. These variables can betweaked to control the size of the gap between the inner and outerlayers. The liquid embolic will be captured in between the two layers,forming a thin film of precipitated solidified material. Where asingle-layer device (e.g. a single layer stent) is used as an embolicscaffold, a large pore size would allow liquid embolic to freely migratethrough the device, which could introduce stroke risk elsewhere in thevasculature. On the other hand, a single-layer device with small poreswould result in liquid embolic being trapped outside of the stent, whichwould make re-sheathing of device very difficult since there would be athick layer of embolic stuck to the device effectively increasing theoverall diameter of the device. In comparison, a multiple-layer sealingdevice 110 including a tighter mesh inner layer and a looser mesh outerlayer—as envisioned in several embodiments of the current invention,would allow for a gap or pocket between the tighter inner layer andlooser outer layer to hold the precipitated or solidified liquidembolic—this configuration is shown in FIG. 9 where trapped embolic 200sits between a loose outer layer 114 a and a tight inner layer 112 a.The sealing device could still be withdrawn since the inner layer wouldstill be able to collapse upon re-sheathing into a catheter since thereis nothing effectively under this inner layer—the act of the inner layercollapsing will help force the outer layer and the embolic pocket toalso collapse, allowing the sealing device to be withdrawn from thevasculature after the liquid embolic has sufficiently occluded theaneurysm. In one example, after the embolic delivery procedure, theproximal end of the sealing device is pinned against microcatheter 128which is used to deliver the sealing device, and the sealing device isretracted into a guide catheter 126 which is used to remove the devicefrom the vasculature.

Another embodiment could utilize an inner balloon and an outer mesh asthe sealing device. The microcatheter used to deliver the sealing devicewould contain an inflation lumen to inflate the balloon once the sealingdevice is placed. The outer mesh could still be self-expandable, or,alternatively, the balloon inflation would prop the mesh open.Alternative embodiments could utilize multiple mesh layers and an innerballoon, or the embodiment of FIGS. 1 with the inclusion of aninflatable inner balloon within the multiple mesh layers. The embolicmay get past the outer mesh layer but would be trapped against theballoon.

In one example, the sealing device has an inner and outer layer. Theinner layer has a diameter of about 4-5 millimeters, while the outerlayer has a diameter of about 4.5-6 millimeters. In one example, theinner layer has a diameter of about 4.2 millimeters and the outer layerhas a diameter of about 4.7 millimeters. Note the difference indiameters between the inner and outer layers provides the pocket or gapdiscussed earlier where any displaced liquid embolic can be trapped orcaught. In one example, the inner and outer layers are comprised of awire mesh where the wires are about 0.0005-0.002 inches in diameter. Theinner layer wires can have a different diameter than the outer layerwires, or the wires comprising both the layers can have the samediameter. In one example, the sealing device is configured so that theinner layer pores are about 50-1000 microns, in one example 75-500microns, in one example about 100-250 microns, in one example about100-150 microns. A larger pore size would allow blood and DSMO throughwhile also expanding the possibility of liquid embolic getting through,while a smaller pore size would be more likely to block the flow ofembolic but an extremely small pore size could block the flow of bloodand DMSO.

Various techniques can be used to make the sealing device. For example,the sealing device can be braided over a mandrel where the mandrelincludes two tapered ends to create the tapered proximal and distalsection shapes shown in FIG. 1 . Alternatively, the sealing device isbraided over a tubular mandrel and a marker band is placed over theproximal and distal ends to create the tapered shape. Please note, asdiscussed earlier, the term taper refers to involving a diameterreduction in a particular direction. For the purposes of FIG. 1 , theparticular shape shown is conical type of taper, though other taperedshapes are possible as will be described.

FIG. 1 show the sealing device with a conically tapered proximal 132 aand distal 132 b section shape. The sealing device can adopt variousshapes, including various proximal and distal section shapes. In oneexample, proximal section 138 a of the sealing device has a conicalshape while the distal section 138 b of the sealing device can have arounded shape—as shown in FIG. 8 . This shape can be achieved, forexample, by utilizing a mandrel with a rounded-end section, where thedistal section is braided over the rounded-end section. Alternatively,the proximal end of the sealing device can have a rounded shape whilethe distal end of the sealing device has a tapered shape. Alternatively,both the proximal and distal ends of the sealing device can have arounded shape. This shape can be created by utilizing a mandrel with tworounded-end sections to create the sealing device.

The following embodiments shown in FIGS. 10-19 and described below haveparticular usefulness in treating aneurysms, including bifurcationaneurysms. Bifurcation aneurysms occur at a vessel bifurcation region.Vessel bifurcations are regions of high blood flow and there is asignificant amount of pressure exerted on the blood vessel wall in thebifurcation region which can lead to the formation of aneurysms.Bifurcation aneurysms represent the vast majority of aneurysms in theneurovasculature, and if these aneurysms rupture complications such asstroke can result. Bifurcation aneurysms can be difficult to treat sincethe geometry of the vessel bifurcation region makes placement of stentsor other devices difficult since the bifurcation region straddlesmultiple blood vessels. Often, two stents are placed across each otherin a procedure known as y-stenting to cover both branches of thebifurcation. The aneurysm itself can be filled with embolic coils, andthe multiple stents retain the embolic coils. Alternatively, two flowdiverting stents may be placed together to limit blood flow to theaneurysm. Two-stent procedures are challenging and costly due to thetime and expense associated with placing multiple stents. Liquid embolicgenerally cannot be used to treat bifurcation aneurysms due to the highrisk of liquid embolic migration prior to solidification or even aftersolidification, where the liquid embolic can migrate elsewhere leadingto major complications. The following embodiments are geared towards asealing device that can be placed within the bifurcation aneurysm oragainst the neck of the bifurcation aneurysm thereby facilitating theuse of liquid embolic.

A bifurcation aneurysm 204 is shown in FIG. 10 . As shown in the Figure,a bifurcation aneurysm 204 occurs at a vessel bifurcation where a parentvessel 206 branches off into vessels 208, 209.

FIG. 11 illustrates an occluder 210 used in a sealing device/system,where the sealing system is particularly beneficial in treatingbifurcation aneurysms. In one embodiment, occluder 210 is formed of aplurality of metallic braided wires. The wires can be made of nitinol,stainless steel, and/or cobalt-chromium. Nitinol is one particularlypreferred material due to its strong shape memory properties. Radiopaquewires (e.g., tantalum, platinum, palladium, and/or gold) can also beincorporated into the braided wire mesh to aid in visibility. Occluder210 is imparted with a heat set shape, where the wires comprising theoccluder 210 are heat set into a particular expanded shape so that theoccluder adopts an expanded shape upon delivery from a catheter. Theoccluder can therefore be thought of as an expandable structure.Occluder 210 includes a distal portion 212 and a proximal portion 214,separated by a band 216. The band is placed over the braid and is usedto create a constriction in the occluder to thereby define the distalportion 212 and proximal portion 214. The band can be composed of ametallic (e.g., nitinol or stainless steel) tube or crimp.Alternatively, a radiopaque marker band (e.g. tantalum, platinum,palladium, gold) can be used to aid in visualization. A distal coil 218is connected to the end of the occluder. Coil 218 preferably has a shapememory coiled shape configured so that when coil 218 contacts the vesselwall, said coil 218 will curl inwards instead of sticking to the wall.In one example, coil 218 is made of nitinol or a radiopaque materialsuch as platinum. When occluder 210 is placed into an aneurysm, coil 218is the first object to contact the aneurysm dome. Coil 218 contacts thedome of the aneurysm and serves as a base structure which the rest ofoccluder 210 opens under. The proximal part of occluder 210 is connectedto a pusher 230. The pusher tube is tubular in shape and contains anopen lumen.

A tension wire 222 runs the length of occluder 210 as shown in FIG. 12 .The distal end of the tension wire 222 connects to distal coil 218. Inone embodiment, the inner surface of coil 218 contains a threadedinterface which the distal end of wire 222 can screw into via mechanicalrotation. This mechanical connection can be achieved in a coupledifferent ways. For instance, the distal end of tension wire 222 couldcontain male threads and a portion of the inner lumen of coil 218 couldcontain female corresponding receivers. Alternatively, coil 218 isplaced over a mating structure and the mating structure contains athreaded interface to mate a corresponding interface on the distal endof tension wire 218. Other embodiments could forego distal coil 218 andinstead just include an interface structure, such as a cap, that thetension wire can mechanically connect to (e.g. via the male/femalethreaded rotation concepts discussed above). Tension wire 222 spans thelength of pusher 230. Pusher 230 is a tube and contains an open lumenspanning the length of the pusher which accommodates tension wire 222,as shown in FIGS. 13-15 . Tension wire 222 and pusher 230 are separatelycontrolled and manipulated by a user from the proximal end of thesystem; the proximal end of tension wire 222 sits proximally beyond theproximal end of pusher 230 so that the tension wire and pusher areindependently pushed/pulled. Pushing or pulling the pusher will push orpull the entire system, while pushing or pulling the tension wire willmanipulate the shape of occluder 210 in a manner which will now bedescribed. The distal part of the tension wire 222 is connected to coil218, but this is the only part of the tension wire 222 connected toanything. Therefore pushing tension wire 222 will exert force on coil218 thereby pushing the coil and the attached occluder 210 therebyelongating occluder 210 so that it takes on the shape shown in FIG. 12 .Pulling tension wire 222 will exert a retracting force on coil 219thereby pulling the coil and the attached occluder 210 back so that theoccluder 210 takes on the compressed shape shown in FIG. 11 . Sincetension wire 222 can be used to manipulate and control the shape of theexpandable occluder 210, wire 222 can be thought of as an expandablestructure controller/control mechanism. Occluder 210 can include foldinglayers where the layers fold into each other as the occluder 210collapses when the tension wire is retracted or pulled. The foldinglayers would allow a significant amount of material to be used on theoccluder, but where the occluder adopts a smaller profile whencompressed allowing for a substantial difference between the compressedand elongated shape of the occluder.

FIG. 13 shows the sealing system, including occluder 210, duringdelivery through a larger delivery catheter 232. In one example,delivery catheter 232 is a 6 or 7 French guide or access catheter andpusher 230 is 2-3 French size—this would represent a relatively largersystem since embolic devices are typically delivered through 2 or 3French size microcatheters. In another example, delivery catheter 232 isa 2 or 3 French size microcatheter, and the pusher is 1-2 French size tobe accommodated within the microcatheter. Occluder 210 is sheathedwithin delivery catheter 232 and is navigated or pushed through deliverycatheter 232 to the treatment site. Occluder 210 takes on an elongatedconfiguration when placed within the delivery catheter due to therestraining force provided by delivery catheter 232, as illustrated inFIG. 13 . The user pushes pusher 230 to navigate the sealing systemthrough delivery catheter 232. Tension wire 222 can also be separatelypushed while pusher 230 is pushed during delivery to keep tension on theoccluder and ease delivery by minimizing the portion of occluder 210contacting the delivery catheter 232 inner wall during delivery, therebyminimizing friction. There is a detachable connection 226 between pusher230 and occluder 210 which can be detached to sever the occluder fromthe pusher, which will be described in more detail later. Element 224represents the attachment mechanism connecting tension wire 222 todistal coil 218.

FIGS. 14-15 show the occluder 210 after being pushed out of deliverycatheter 232. Occluder 210 will adopt an expanded configuration afterbeing released from delivery catheter 232 due to the enlarged heat setshape imparted into the occluder. In FIG. 14 , tension wire 222 ispulled to collapse the shape of occluder 210, thereby enabling theoccluder to adopt a longitudinally contracted, radially expanded shape.Occluder 210 would be delivered to the target treatment site, andtension wire 222 is then pulled to collapse the shape of occluder 210 inorder to fit the shape of the treatment area. When the shape of occluder222 is appropriately configured for the treatment area, tension wire 222is withdrawn—in the embodiment where the tension wire is a mechanicallyscrewing connection, the tension wire can simply be unscrewed and thenpulled out from pusher tube 230—as shown in FIG. 16 . The tension wirewould preferably be pushed/pulled so that the proximal portion 224 ofoccluder 210 is as wide as possible to conform to the bottom portion ofthe aneurysm 236 while still fitting within said aneurysm. Since theoccluder proximal portion 224 would generally abut or be near theaneurysm neck, it should be as wide as possible to prevent embolicmigration past this layer.

Once the wire is withdrawn, pusher tube 230 can be used to deliveradditional embolic agents, including liquid embolic and/or other agentsincluding embolic coils or meshes. In FIG. 17 , pusher tube 230 is usedto deliver liquid embolic 234. It is beneficial to remove tension wire222 from pusher 230 prior to embolic delivery in order to maximize thelumen space for embolic delivery, however, if tension wire 222 issufficiently narrow then it might not be necessary to remove tensionwire 222 prior to embolic delivery. The liquid embolic is delivered intothe target treatment site. The liquid embolic, delivered in a liquidform, will easily pass through the pores of occluder 210. The pores ofoccluder 210 will also allow the DMSO to diffuse out of the occluder, asthe DMSO diffuses from the liquid embolic after delivery. The porousmesh occluder 210 will also allow blood to flow through, as blood isdisplaced due to delivery of the liquid embolic. As the liquid embolicis exposed to blood, the embolic starts to precipitate. As the embolicprecipitates, it gets more viscous and can no longer pass through thepores of occluder 210; the embolic then solidified and occludes thetarget space. The embolic, therefore, is contained within theaneurysm/treatment site. In one embodiment, occluder 210 includes apolymer coating to further aid in embolic retention; the polymer coatingwould increase the thickness of occluder 210 and reduce the pore size,therefore offering some additional advantages in embolic retention. Thepolymer coating can be applied in selective places along the occluder210, so that there are still porous openings present to allow diffusionof blood and DMSO through occluder 210. In one embodiment, the mesh ofproximal section 214 is less porous than the mesh of distal section 212;this can be achieved by utilizing smaller pores on proximal section 214,which would ensure that liquid embolic is less likely to pass throughproximal section 214 and permeate beyond the aneurysm. In oneembodiment, the polymer coating could be utilized solely along theproximal section mesh 214 in order to decrease the porosity in thisregion to help prevent embolic passage past this region. In one example,the mesh pore sizes are configured so that they are about 50-1000microns, in one example about 75-500, in one example about 100-250microns, in one example about 100-150 microns.

After the liquid embolic 234 is delivered and precipitates, pusher tube230 is withdrawn. There is a detachment junction 226 between pusher 230and occluder 210 which can be severed to separate said pusher from saidoccluder. Various types of detachment systems can be used, for instancemechanical, thermal, or electrolytic systems. U.S. Pat. No. 8,182,506,US20060200192, US20100268204, US20110301686, US20150289879,US20151073772, US20150173773 all of which are hereby incorporated byreference in their entirety, disclose various detachment systems thatcould be used with the present concept. Detachment junction 226 includesa severable linkage, for example a detachable tether or degradablesubstance which degrades thermally, mechanically, or electrolytically toeffect detachment of the occluder. In one example, the user wouldactivate a user interface (i.e. button) to degrade a portion of thedetachment junction to effect detachment between the pusher 230 andoccluder 210.

FIGS. 18-19 show the treatment procedure within a bifurcation aneurysm236. The sealing system is delivered through blood vessel 238 intobifurcation aneurysm 236. Due to the manipulatable shape of occluder210, the occluder sits physically within the vessel and preventssubsequently delivered liquid embolic from seeping out.

In one embodiment, the distal portion 212 of occluder 210 sits withinthe aneurysm and proximal portion 214 of occluder 210 sits outside ofthe aneurysm, proximal section 214 would in essence act like a neck sealensuring embolic does not escape the neck of the aneurysm. In anotherembodiment, occluder 210 sits completely outside the aneurysm and thewhile occluder acts like a neck seal or catch sitting flush with theneck of the aneurysm and preventing embolic from migrating.

Arterio-venous malformations (AVM's) are abnormal connections which formbetween the arteries and veins. Arteries supply oxygen-rich blood fromthe heart to various areas of the body, while veins return oxygen-poorblood to the heart. Capillaries normally connect arteries and veins,allowing the exchange of oxygen, water, and nutrients with the brain andbrain tissue. AVM's often take form as a tangled mass of connections,which bypass the normal capillary system entirely, bypassing normalbrain tissue and interfering with natural blood flow. The vascularabnormality of malformed blood vessels is typically referred to as thenidus. AVM's can form in a number of locations but often form in thebrain, and there is a risk of hemorrhage which can result in stroke.AVM's, like capillaries, contain an arterial side (connecting to thearteries) and a venous side (connecting to the veins).

FIG. 20 a shows a normal arterial-capillary-venous intersection,comprising an arterial-side 310, venous-side 312, and capillaries 314which connect the arteries and veins. FIG. 20 b shows an AVM 316, whichis an abnormal connection between arteries and veins bypassing thenormal capillary structure. The AVM includes nidus 311, feeder vessels313, and draining vein 312. Nidus 311 is an abnormal tangle of bloodvessels which draws blood flow away from the capillaries, feeder vessels313 feed blood into the nidus and away from the capillaries, while anenlarged draining vein 312 provides a flow path out of the nidus intothe normal venous system—note since the AVM bypasses the normalcapillary system, a draining vein is generally needed to drain the bloodinto the actual venous system to provide outflow for blood. AVM's areunnatural connecting structures and interfere with the normalcirculation pattern, drawing blood away from the capillaries. Over time,AVM's can hemorrhage which can lead to various complications. Pleasenote, AVM's can take on extremely tortuous shapes with many differentconnections, for the ease of illustration with the proposed treatmentconcept, a relatively “simple” AVM shape is shown in FIGS. 21-24 .

Please note, blood in the artery would flow in the direction of theAVM/capillary, while blood in the veins would carry blood away from theAVM/capillaries. So, in FIGS. 20-22 , blood would generally flow left toright—from the artery to the vein, as indicated by the arrows 317 inFIGS. 21-24 .

AVM's can occur in various locations throughout the body, including inthe neurovasculature and the brain. Neurovascular AVM's are particularlyproblematic and can rupture leading to stroke. Some treatment proceduresto treat AVM's involve occluding AVM's with liquid embolic so that bloodflow bypasses the AVM and normal circulation is restored. In the typicalprocedure, a microcatheter connected to a liquid embolic is trackedthrough the arterial vasculature to the arterial side of an AVM, nearthe nidus. Liquid embolic is then injected through the microcatheter andinto the AVM. The liquid embolic hardens or solidifies, blocking offpassage of blood through the AVM and restoring flow to the capillariesand normal circulation.

One issue with the traditional method of liquid embolic delivery is thattoo much liquid embolic may be delivered and some embolic may migrateout of the AVM, or the embolic may migrate before hardening and migratethrough the AVM and into the venous system. In situations where the AVMis located in the neurovasculature and liquid embolic is used to treatthe AVM, the neurovasculature venous path drains into the pulmonarysystem—so embolic in the venous system can potentially end up in thelungs, leading to major complications. Embolic solidifying in the venousflow path can also close the natural outflow of blood, which can causethe AVM to rupture.

The typical liquid embolic delivery procedure involves gaining accessthrough the arterial vasculature through the femoral artery. The generalprocedure involves using a guidewire which is navigated up through thefemoral artery to the vicinity of the treatment site. A guide or accesscatheter is tracked over the guidewire to access the part of thevasculature containing the AVM. A smaller microcatheter is then trackedthrough the guide or access catheter to the actual treatment site—forinstance, through one of the feeder vessels and into the AVM. A proximalpart of the microcatheter (the microcatheter hub) is connected to aliquid-embolic containing syringe, and the liquid embolic is deliveredfrom the syringe, through the microcatheter, and then into the AVM. FIG.22 shows this traditional method of delivery, where microcatheter 318 ispassed through the arterial side 310 of AVM 316. Microcatheter 318 isplaced in/near the nidus of the AVM and liquid embolic 320 is deliveredinto the AVM. Since liquid embolic is delivered from the arterial sideof the AVM, the embolic is delivered in the direction of blood flow (seearrows 317 in FIG. 22 ), making it more likely that the embolic will bepushed with the direction of blood flow out of the AVM and into thevenous system.

The more specific typical delivery procedure would involve using anintroducer to gain access to the femoral artery. A guidewire is thenused to navigate to the treatment site. This would involve traversingthe femoral artery, external iliac artery, descending aorta, aorticarch, and internal carotid arteries where the guide or access catheteris tracked over the guidewire. Beyond the carotid arteries are theneurovascular arteries which are typically fairly small so generally amicrocatheter would then be tracked through the guide or access catheterand used to access the smaller neurovascular arteries including theparticular region where the AVM is. The microcatheter is navigated tothe AVM, preferably to the feeder vessel leading to the nidus of theAVM. Liquid embolic is then delivered from a syringe mated to themicrocatheter hub into the AVM to embolize the AVM. Alternatively,access can be achieved by the introducer gaining access from the carotidartery then navigating to the AVM from the carotid artery.

One way to deal with the issue of embolic migration which iscontemplated in the present invention involves delivering the embolicfrom the venous side 312 of AVM 316 as shown in FIG. 23 —instead of fromthe arterial side 310 as per the typical embolic delivery procedureshown in FIG. 22 . The femoral vein or jugular vein is used to accessthe venous vasculature, and a guidewire and guide catheter are trackedthrough the venous system to a location near the AVM 316. Amicrocatheter 318 is tracked through the guide or access catheter to thevenous side 312 of AVM 316, for instance through the draining vein ofthe AVM. Liquid embolic 320 is then delivered from a syringe coupled tothe hub of microcatheter 318 through the microcatheter lumen and intothe AVM 316. Since the delivery is from the venous side 312 of AVM 316,the microcatheter placement and liquid embolic delivery will be againstthe flow of blood, where the arterial to venous flow of blood isindicated by arrows 317 in FIG. 23 . Since liquid embolic 320 isdelivered against the flow of blood and since liquid embolic is moreviscous than blood, liquid embolic will not permeate past the AVM intothe arterial system. The relatively high viscosity of liquid emboliccompared to blood makes embolic backflow or reflux unlikely even incircumstances where the liquid embolic is delivered against the naturalblood flow, however, the microcatheter includes a catch or shieldstructure 322 to catch any embolic that happens to reflux.

In one example, an introducer is used to gain access through the femoralvein, and a guidewire is used to track through the venous system. Aguide or access catheter is then navigated through venous system overthe guidewire to the location of the AVM, this would include navigatingthrough the femoral vein, iliac vein, vena cava, through the jugularvein. A microcatheter would then be used to locate the actual region ofthe AVM, where the microcatheter could be tracked over the guidewire.The microcatheter is preferably placed near/in the drainage vein of theAVM where liquid embolic is then delivered from the microcatheter intothe AVM. In another example, access is gained directly through thejugular vein (instead of the femoral vein) and the microcatheter is thennavigated through the treatment site.

Placing a microcatheter in the venous system would require deliveryagainst the flow of blood. The microcatheter could be configured fordelivery through the venous system by having augmented pushing strengthfor venous delivery. Microcatheters typically use structuralstrengthening features such as coils, braids, and particular polymers toaugment either pushing strength or flexibility, so these parameterscould be tailored for venous delivery.

Another way of dealing with the issue of embolic migration, contemplatedin the present invention, involves delivering embolic from the arterialside 310 of the AVM but placing a catch or shield on the venous side ofthe AVM to catch any migrating embolic—as shown in FIG. 24 . This wouldinvolve the use of two microcatheters—a first microcatheter 319 a usedto deliver liquid embolic is delivered to the arterial side 310 of AVM316 while a second microcatheter 319 b with catch 322 is delivered tothe venous side 312 of AVM 316. The liquid embolic is injected throughmicrocatheter 319 a placed on the arterial side of the AVM, in thedirection of blood flow as indicated by arrows 317—this is similar tothe traditional delivery procedure. However, unlike in the typicaldelivery procedure, microcatheter 319 b and catch/shield 322 are placedon the venous side of the AVM and will catch any migrating embolic. Inone example, vascular access is gained through the femoral artery andthe microcatheter 319 a is tracked through a guide or access catheter tothe arterial side 310 of AVM 316. Vascular access for microcatheter 319b is gained through the femoral or jugular vein where microcatheter 319b is tracked through a guide or access catheter to the venous side 312of AVM 316.

Another embodiment which would deal with the issue of embolic migrationis conceptually similar to the embodiment of FIG. 24 , except bothmicrocatheters 319 a and 319 b would deliver liquid embolic. Bothmicrocatheters 319 a and 319 b are connected to liquid-emboliccontaining syringes, where said syringes are mated to the microcatheterhubs. Liquid embolic would be delivered through both microcatheters andinto the AVM 316, from opposite sides of AVM 316. In this embodiment,rather than relying on embolic occlusion from one side of the AVM, theAVM would be occluded from both sides which would offer some advantagesto ensure successful occlusion of the AVM. The presence of the catch orshield structure 322 on microcatheter 319 b would ensure any embolicthat might migrate from AVM 316 into the venous system would be trappedby shield 322.

FIG. 23 shows a microcatheter 318 with a catch or shield 322. Themicrocatheter has an inner lumen for injection/delivery of embolicmaterial. The microcatheter inner lumen can accommodate a guidewire thatpermits navigation and guiding of the microcatheter such that themicrocatheter can be tracked over the guidewire and through the guide oraccess catheter. In one embodiment, the catch or shield 322 is comprisedof a mesh of metallic wires. The mesh could comprise nitinol wires,braided together to form the shield—nitinol is a material withparticularly good shape memory retention properties. Alternatively,radiopaque (i.e. gold, platinum, tantalum, palladium) wires could beincorporated along with the nitinol wires in the mesh in order to aid invisualization. Shield 322 could also comprise various materials such ascobalt-chromium, stainless steel, polymers. Shield 322 is preferablycomprised of biocompatible materials since the shield will be placedwithin the vasculature. The mesh preferably has smaller pores; the poresize should be large enough to allow relatively unimpeded flow of bloodand DMSO, but small enough to prevent the passage of the heavier andmore viscous embolic material—especially as the liquid embolic starts togets thicker and solidify after exposure to blood. In some examples, thepore size could be about 50-1000 microns, about 75-500 microns, about100-250 microns, or about 100-150 microns. The shield can be thought ofas a tight-knit mesh/braid basket meant to catch embolic material. Theshield will trap the liquid embolic agent as it is precipitating, whilepermitting flowing blood to still pass through the shield until the AVMis fully occluded—once the AVM is fully occluded there will be minimalor no blood flow through the AVM due to the occluding effect of thesolidified embolic. In one example, the user would inject the liquidembolic until the embolic fills past the AVM nidus on the arterial sideto penetrate the arterial feeder vessels to shut off the blood flow intothe AVM, eliminating any blood flow path into the AVM. Once the AVM isfully occluded, the risk of an AVM rupture is low since there is nolonger any blood flow into the AVM. Additionally, once the liquidembolic has precipitated or solidified, the embolic should stay in placesince it will be a homogenous solidified mass occluding the AVM.Different embodiments could also utilize a variable pore size along thelength of shield 322 where, for instance, a distal portion of shield 322(the part closer to AVM 316) can utilize a higher porosity than a moreproximal portion of shield 322—due to the conical shape of shield 322,this would mean the outer distal region of the shield would be morepermeable than the inner proximal region of the shield. In practice,this should funnel blood and DMSO through the outer, more-porous part ofthe shield while the inner, less-porous part of the shield would offerincreased resistance to blood and DMSO flow, such a configuration couldmaximize the chances of catching embolic since the catch as a wholewould offer more resistance to flow since only a particular region ofthe shield would allow relatively unimpeded flow of blood and DMSO.

FIGS. 25-27 shows microcatheter 318 and catch/shield 322 a-322 c wherethe shield has a number of different shapes—the shield can take on anumber of shapes including parabolic, linear, conical type profiles asshown in the figures. The shapes could take on the shape similar to thatof a satellite dish (parabolic) or a noise-projecting megaphone(linear/conical type profile). Please note, the side profile of theshield is shown, and the shield sits around a distal portion of themicrocatheter, so the shield sits radially around the microcatheter.FIG. 25 shows a truncated-conical type shield shape 322 a where thedistal portion of the shield expands radially out like the base of acone, similar to a megaphone. In FIG. 26 , shield 322 b has a moreelongated shape, where the proximal part of the shield tapers outwardand the distal section of the shield has a relatively consistent shapeand/or diameter. In FIG. 27 , shield 322 c adopts a more trumpetedshape. The shield could have one layer or multiple layers—for example amesh could be folded back over onto itself, or folded under itself, tocreate a multiple layer mesh. Alternatively, multiple meshes couldoverlap and be attached together to create a multiple layer mesh. Theshield could sit around the distal tip of the microcatheter, or sitaround a point a bit proximal of the distal tip—but nonetheless shouldsit toward the distal region of the microcatheter. The distal end of theshield could sit flush with the distal tip of the microcatheter, sitpast the distal tip of the microcatheter, or sit proximal of themicrocatheter distal tip. Please note, the shield shapes are shown anddescribed for illustrative ease, but in practice a number of differentshapes could be used for shield 322.

Microcatheter 318 is delivered through a larger access or guidecatheter, as described earlier. The larger access/guide catheter wouldprovide the restraining force to collapse the shield during delivery.When microcatheter 318 is freed from the delivery catheter, the shieldwould adopt its natural unfurled shape. Preferably, the shield iscomprised of material with good shape memory so this natural unfurledshape is set within the shield's shape memory. Nitinol, as discussedabove, has good shape memory properties—in one example, the mesh shield322 includes nitinol which is heat seat into its expanded shape. Onceshield 322 is freed from the larger access/guide catheter, the shieldwill naturally adopt its expanded shape due to the imparted shapememory. In one embodiment, the shield configuration in the delivered andexpanded state are similar—that is, in the delivered state whenmicrocatheter 318 and shield 322 are housed within a larger guidecatheter, the shield simply adopts a compressed position where it ispressed against microcatheter 318. Shield 322 would then expand outwardonce said shield 322 is unconstrained by the guide/access catheter.

In an alternate embodiment shown in FIGS. 28-30 , shield 322 adopts afirst inverted configuration while sheathed in the larger access/guidecatheter 334, and a second unfurled position after being released fromthe said access/guide catheter 334. FIG. 28 shows microcatheter 318 withshield 322 attached to a distal portion of said microcatheter 318,within a larger access/guide catheter 334. Shield 322 is attached atlocation 336 to microcatheter 318. Section 338 of shield 322 representswhat would be the distal part of shield 322 when said shield is fullyexpanded and free of the larger guide catheter 334—as shown in FIG. 30 .When microcatheter 318 is housed within guide catheter 334, section 338of shield 322 folds back and sits proximal relative to section 336,which is where the shield 322 is attached to microcatheter 318. FIG. 29shows an in-between position where a portion of microcatheter 318 exitsguide catheter 334, but the shield is still in an inverted positionsince the microcatheter 318 has not advanced to a point where the shielditself is free of larger guide catheter 334. Microcatheter 318 would bepreloaded within guide catheter 334 so the shield adopts the invertedconfiguration, or the user could load microcatheter 318 through guidecatheter 334, but the user would ensure this shield is inverted duringplacement.

In one embodiment, shield 322 is not detachable from microcatheter 318.With this embodiment, the liquid embolic would be delivered (as shown inFIG. 23 ). After the embolic is delivered through microcatheter 318 andsolidifies, and any refluxed embolic is caught by shield 322,microcatheter 318 with integral shield 322 is withdrawn. However,generally it would be preferable to have a detachable shield so the userhas the option of leaving the shield 322 in place to catch any embolicwhich might migrate in the future—or to address circumstances where thepresence of the embolic in the shield may make retraction of shield 322difficult.

In one embodiment shield 322 is detachable from microcatheter 318. Theshield, if detached, would remain in the vasculature as an implant andthe catheter would be withdrawn. However, the user could decide not todetach the shield—for instance, if confident that the embolic hadsolidified and would not migrate through the venous system, or if noembolic had refluxed and the shield was relatively free of embolic.Embolic would be delivered through microcatheter 318, and any migratingor refluxed embolic would be caught in shield 322. The user could detachshield 322 and retract microcatheter 318—leaving the shield in place incase any additional embolic migrates or refluxes. Shield 322 wouldtherefore remain as a permanent implant. Alternatively, the user coulddecide not to detach shield 322 and instead retract microcatheter 318along with connected shield 322. In one example, the user could retractmicrocatheter 318 and shield 322 through guide catheter 334; in anotherexample, the user could retract a portion of microcatheter 318 throughguide catheter 334 but leave shield 322 distal of the guide catheter andretract the system in this manner through the vasculature. Shield 322 ispreferably made of biocompatible materials, such as the nitinol wiresdiscussed earlier, since the shield would become an implant if detached.However, the shield could also be detached and subsequently retrieved.

FIG. 31 shows a microcatheter 318, shield 322, and detachment systemused to detach shield 322 from microcatheter 318. Shield 322 ispreferably set near the distal tip of microcatheter 318. The distal partof shield 322, as discussed earlier, could sit flush with the distal tipof microcatheter 318, sit past the distal tip of microcatheter 318, orsit proximal of the microcatheter 318 distal tip. An electrolyticdetachment system is shown in FIG. 31 . Microcatheter 318 includes ametallic coil 332 which sits around the outer diameter of themicrocatheter or is placed within the microcatheter 318 tube wall. Themetallic coil can be made of a number of materials, such as stainlesssteel. The coil is used to provide structural strength to the catheter,and will also convey current through the coil. A voltage source 330 isplaced at the proximal end of the system and provides a positive currentsource, in one example the voltage source is a DC power supply. Anadhesive pad can be stuck to the patient, so the patient himself orherself (via the bloodstream) is the ground. The catheter metallic coil332 culminates in a metallic (i.e. stainless steel) marker tube insert326 which connects to coil 332. Shield 322 connects to a fused junction324 which can be a polymeric or metallic element. The fused junctionconnects shield 322 to microcatheter 318 and can crimp over shield 322.The marker tube insert 326 contains a small laser-cut groove 328, thisgroove provides a thinned, weakened region in the insert which speeds upthe electrolytic detachment of shield 322 from microcatheter 318.Anything distal of groove 328 should fall off and remain in thebloodstream along with shield 322 once the detachment sequenceinitiates. The electrolytic detachment occurs when the current from thepower supply goes through coil 332, through the marker tube insert 326,through the patient bloodstream where the patient's blood provides theionizing fluid media for the electrolytic detachment. When thedetachment sequence initiates, microcatheter 318 and shield 322 arealready in the blood vessel so they are already exposed to blood. Theuser would interact with the voltage source 330—in one example there canbe a button or some user interface to detach shield 322 when desired.

Alternative embodiments could utilize other detachment systems—includingmechanical, thermal, or other electrolytic concepts. For example, amechanical system could be used where a screw can be rotated which wouldloosen a distal shield connection to effect shield detachment.Alternatively, a thermal detachment system could be used where thecatheter structural coil 332 connects to a heater coil which sits over atether, and the heater coil when heated severs the tether to detach theshield. Alternatively, a thermal detachment system could be used wherean adhesive is heated and melts to effect detachment of the shield.Alternatively, the structural coil 332 could connect to a capsuleelement and the capsule element itself would contain either a severabletether or an electrolytically degradable linkage within said capsule todetach the shield. U.S. Pat. No. 8,182,506, US20060200192,US20100268204, US20110301686, US20150289879, US20151073772,US20150173773 all of which are hereby incorporated by reference in theirentirety, disclose various detachment systems that could be used withthe present concept. Different embodiments could also utilize a proximalbattery with a positive and negative terminal, and catheter structuralcoils or wires running from the battery to shield 322 to the degradablelinkage, where degradation of the degradable linkage detaches shield322.

FIGS. 32-34 show an alternative embodiment involving a catch/shieldstructure which addresses potential friction issues that might otherwisearise when tracking a catch/shield structure through a largeraccess/guide catheter. This embodiment utilizes a mechanism to ensure ashield structure adopts a first elongated, collapsed state where itdirectly abuts the attached microcatheter during delivery, and thenadopts an expanded shape later. In this embodiment, microcatheter 340 isstructurally comprised of a braid of wires and part of the braid ofwires ferries current from a proximal voltage source (e.g., a battery).One wire can supply positive current, while the other wire can supplynegative current. In one example, a highly conductive material such asberyllium-copper can be used for the braid wires. Microcatheter 340includes a proximal section 340 a, a distal section 340 b, and a heaterelement 344 in between. The heater 344 can be a laser-cut hypotubepatterned in a circular shape with a serpentine pattern defining thecircular shaped heater. The advantage of such a pattern is that the heatwould be generated as the current travels through the serpentine shapearound the circular pattern. Shield or catch structure 342 sits distalto this heater, where portion 342 b is permanently attached to thedistal tip of the microcatheter 340 and portion 342 a is temporarilyattached to a section of the microcatheter sitting near heater 344.Bonding polymeric material such as Engage, Pebax, or other low-melttemperature material can be used as the bonding material. When theheater 344 is heated, the bonding material near the heater melts and theshield adopts the shape shown in FIG. 33 as portion 342 a of the shieldis no longer bonded but portion 342 b is still affixed to the distal tipof microcatheter 340. The physician can retract the microcatheter tocause the shield to invert and point distally as shown in FIG. 34 —inthis configuration portion 342 b is still affixed to the distal tip ofthe microcatheter, however portion 342 now flips and sits distally pastthe microcatheter. The shield is preferably heat set into the shapeshown in FIG. 34 to induce the shield to adopt this inverted shape oncemicrocatheter 340 is retracted and after the portion of shield 342 is nolonger affixed near heater 344. Shield 342 can be comprised of a nitinolbraid and optionally coated with ePTFE, the inclusion of ePTFE on theshield—or the inclusion of ePTFE in shield section 342 a—will help thebonding polymeric material hold the shield 342 in its collapsed stateshown in FIG. 32 .

Please note the various embodiments shown in FIGS. 1-34 and presentedherein discussed various devices, systems, and methods used to preventliquid embolic passage where liquid embolic is used for therapeuticeffects in the vasculature—including for use in treating aneurysms andAVM's. All of the embodiments presented utilize a conduit to deliverliquid embolic, the conduit/conduits (e.g. microcatheter 130 of FIG. 1 ,pusher 230 of FIGS. 11-19 , microcatheter 318 of FIG. 23 ) can bethought of as liquid embolic delivery conduit/conduits or liquid embolicdelivery medium/media.

Please note any measurements, materials, drawings provided are meant tooffer illustrative examples of the embodiments described herein and arenot meant to expressly limit the embodiments to what is literally shownand/or recited. Though the embodiments were primarily presented for usewith liquid embolic and offered particular advantages when used withliquid embolic in order to prevent liquid embolic migration, additionalembolic agents such as embolic coils and embolic meshes could also beused where the devices would help prevent embolic agent migration.

Although the invention has been described in terms of particularembodiments and applications, one of ordinary skill in the art, in lightof this teaching, can generate additional embodiments and modificationswithout departing from the spirit of or exceeding the scope of theclaimed invention. Accordingly, it is to be understood that the drawingsand descriptions herein are proffered by way of example to facilitatecomprehension of the invention and should not be construed to limit thescope thereof.

What is claimed is:
 1. A treatment catheter, comprising: a catheterbody; a heater located at a distal region of the catheter body; and, aradially expandable shield connected at the distal region of thecatheter body; wherein activation of the heater causes radial expansionof the shield.
 2. The treatment catheter of claim 1, wherein activationof the heater releases attachment of at least a portion of the shield.3. The treatment catheter of claim 2, wherein the shield is a braidedmesh positioned around an outside of the catheter body.
 4. The treatmentcatheter of claim 2, wherein the shield is attached to the catheter bodyby a permanent attachment area and a heat-releasable attachment area. 5.The treatment catheter of claim 4, wherein the permanent attachment areais located distal of the heater and wherein the heat-releasableattachment area is located near the heater.
 6. The treatment catheter ofclaim 5, wherein the heat-releasable attachment area is composed ofEngage or Pebax.
 7. The treatment catheter of claim 2, wherein thecatheter body is adapted to deliver a liquid embolic agent and whereinthe shield is adapted to block movement of at least some liquid embolicagent.
 8. The treatment catheter of claim 2, wherein the heater iscircular shaped.
 9. The treatment catheter of claim 2, wherein theheater is serpentine shaped.
 10. The treatment catheter of claim 2,wherein the shield is heat-set to form an inverted shape whenunrestrained.
 11. The treatment catheter of claim 2, wherein the shieldcomprises conductive wires connected to a proximal voltage source.
 12. Atreatment catheter, comprising: a catheter body having a liquid embolicagent delivery passage; a heater located at a distal region of thecatheter body; and, a radially expandable shield connected at the distalregion of the catheter body; wherein activation of the heater generatesheat that releases a portion of the shield such that the shield radiallyexpands.
 13. The treatment catheter of claim 12, wherein the shield is abraided mesh positioned around an outside of the catheter body.
 14. Thetreatment catheter of claim 13, wherein the shield is attached to thecatheter body by a permanent attachment area and a heat-releasableattachment area.
 15. The treatment catheter of claim 14, wherein thepermanent attachment area is located distal of the heater and whereinthe heat-releasable attachment area is located near the heater.
 16. Thetreatment catheter of claim 15, wherein the shield is adapted to blockmovement of at least some liquid embolic agent.
 17. The treatmentcatheter of claim 16, wherein the shield is heat-set to form an invertedshape when unrestrained.
 18. The treatment catheter of claim 17, whereinthe shield comprises conductive wires connected to a proximal voltagesource.
 19. The treatment catheter of claim 17, wherein the heater isserpentine shaped.
 20. A treatment catheter, comprising: a catheterbody; a means for generating heat; and, a shield means for blockingliquid embolic agent and for radially expanding when at least partiallyreleased from the catheter body.